Wilms' tumor is a pediatric kidney tumor that occurs as a result of deactivation of both allele of the Wilms' tumor gene (WT1) located on chromosome 11p13 (Call, K. M., et al., Cell 60: 509, 1990). A non-coding upstream sequence of WT1 (C. E. Campbell, et al., Oncogene 9: 583-595, 1994) and a coding region that includes the intron (D. A. Haber, et al., Proc. Natl. Acad. Sci. USA, 88: 9618-9622, 1991) have previously been reported, and they are expected to be involved in the growth and differentiation of the tumor and so forth (D. A. Haber, et al., Proc. Natl. Acad. Sci. USA, 88: 9618-9622, 1991).
However, it was not known that WT1 is involved in the growth of leukemia cells, and that an antisense oligonucleotide derivative to WT1 suppresses and inhibits growth of leukemia cells.